I would figure if there is AI labeling that some things will confuse the system and will be sent to a human. And some things will randomly be sent to a human for error checking. Same thing with Alexa, I figure there's always a low probability chance that anything I say to her will end up reaching a human. She's not always listening as some people fear (the data use would have been detected long ago if she were), but humans occasionally trigger her accidentally--and such errant triggers will be more likely to be sent to a human because they are not going to make sense.